It is well-known that a wide variety of compounds containing carboxylic acid functions are biologically active. For example, such structure is characteristic of non-steroidal anti-inflammatory/non-narcotic analgesic agents such as indomethacin, aspirin, naproxen and the like; cephalosporin antibiotics, e.g. cefmetazole, cefazolin, cephalexin, etc.; penicillin antibiotics such as ampicillin, amoxicillin, hetacillin and the like; as well as other compounds having diverse properties and structures (e.g. captopril, an anti-hypertensive; carbidopa, a peripheral decarboxylase inhibitor; chlorambucil, an antineoplastic; protaglandins E.sub.1, E.sub.2 and F.sub.2.alpha. ; and numerous others).
Nevertheless, it is also well-known that such prior art compounds are characterized by certain inherent disadvantages, notably serious bioavailability and physiological availability problems upon administration. Such reduced availability is attributed in part to significant ionization of the carboxylic acid functional group at physiological pH, which results in the fact that such compounds are poorly absorbed through lipid-water membrane barriers and are irritating.
Thus, a clear need exists for new derivatives of the known bio-affecting acids which will be devoid of the disadvantages inherent in those prior art compounds.
A few compounds structurally related to certain compounds of formula (I) have been reported in the literature. Thus, Bohme and Backhaus, in Liebigs Ann. Chem. 1975, 1790-1796 and Liebigs Ann. Chem. 1975, 1952-1955, describe acyloxymethyl(dialkylamines) wherein the acyl group is ##STR2## and wherein the alkyl groups are each methyl. Volz and Ruchti, in Liebigs Ann. Chem. 1977, 33-39 describe compounds of the type ##STR3## wherein R" is D, H.sub.3, CD.sub.3, C.sub.6 H.sub.5, C.sub.6 H.sub.5 -Cl(m), CH.sub.2 OCH.sub.3, CH.sub.2 Cl and CHCl.sub.2. Also, in "Iminium Salts in Organic Chemistry", ed. H. Bohme and H. G. Viehe, From Advances in Organic Chemistry, ed. E. C. Taylor, Volume 9, Part 1, John Wiley & Sons, Inc., acyloxymethyl(dimethylamines) where the acyl group is acetyl, chloroacetyl, trichloroacetyl and trifluoroacetyl are described, as are the compounds ##STR4## However, none of the publications disclose any utility for the compounds described therein. There is no disclosure or hint of any kind in the literature that such compounds would have pharmaceutical or other bio-affecting utility, or that they would be highly advantageous delivery systems for their parent acids. Also, many of the prior art compounds, e.g. the dimethylamines, are very unstable and difficult to purify, thus would be unsatisfactory for purposes of the present invention. Yet, apparently no systematic investigation was made to find a way to stabilize those compounds.